[Coco] Fwd: IP packets on my coco

[RETRO Innovations]

   IRQs are allowed, but only in memory mapped mode, which require 4k of
   mapping.  Given the requirements of memory mode, most folks map the
   cs8900a in IO mode, which means IRQs are not supported (nor is EEPROM).

     On June 9, 2016 at 11:19 AM "John W. Linville"
     <linville at tuxdriver.com> wrote:
     On Wed, Jun 08, 2016 at 11:38:23AM -0500, RETRO Innovations wrote:

     On 6/7/2016 4:16 PM, John W. Linville wrote:

     On Tue, Jun 07, 2016 at 12:40:29AM -0500, RETRO Innovations wrote:

     On 6/7/2016 12:31 AM, Stephen H. Fischer wrote:

     What the ????
     I see the board image but it quickly is replaced with (Soft Porn?)

     Hmmm, not sure what is going on there... It didn't do that for me,
     butpostimage looks to be putting ads on the side...
     Anyway, here is another version, off my web site, no ads:
     http://go4retro.com/downloads/CocoNIC.png

     Ah...well, that is very tempting. What do I have to do to get one??
     John

     No big deal to get one prototyped. The main question is:
     rtl8019 or cs8900a
     * cs8900a pros
     o a bit more code available from the 65XX crowd
     o Slightly easier to produce, as I have all parts here.
     o AutoCRC?

     The datasheet I find on the web makes it very clear that the chip
     can generate CRC on transmit.

     * cons
     o No IRQ capability. You must poll for all packets

     Why is this? The datasheet clearly shows IRQ lines -- not surprising
     since the part was designed for the ISA bus.

     o More expensive to produce (cs8900a is ~$10/pc)
     * rtl8019 pros
     o IRQ capability
     o A bit cheaper to produce ($rtl8019 is ~$5.00/pc)
     * cons
     o A bit less code from the 6XXX crowd
     o A bit tougher to produce, as I need to source the parts (not a
     huge deal)
     o No AutoCRC?

     Bit 0 of the Transmit Configuration Register would seem to offer CRC
     generation on transmit.

     I know the 65XX crowd laments the lack of cs8900a IRQ, but the
     design is
     proven. So, I leave it up to the community.

     I have no idea what design issue might have painted them into this
     corner, but the datasheet suggests that this shouldn't be a general
     issue with the chip.
     John
     --
     John W. Linville Someday the world will need a hero, and you
     linville at tuxdriver.com might be all we have. Be ready.
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